Compression-expansion air cycle for clothes dryers



R. V. KLINT May 1, 1962 COMPRESSION-EXPANSION AIR CYCLE FOR CLOTHES DRYERS Filed June 16, 1960 H\S ATTORNEY United States Patent 3,3l,77l CGMPRESSIQN-EXPANfilON AIR CYCLE Frlllii CLQ'IHES ERYERS Robert V. iilint, Rexiord, Nil-1., assignor to General Electric (Iornpany, a corporation of New Yori; Filed lune 16, 196i Ser. No. 36,562 8 Claims. (Cl. 34-47) This invention relates to clothes dryers, and more particularly to a clothes dryer of the type using an air cycle wherein a substantial amount of the energy used to evaporate liquid contained in the clothes being dried is retained in the machine for re-use.

At the present time, commercially available clothes dryers fall into two general categories: (l) The type in which air is heated, passed through the clothes, and then exhausted to atmosphere; (2) The type wherein a closed air cycle is used, and the air is dried after it is passed through the clothes dryer by the use of a cold water condensing system which cools the air and thus causes condensation of the moisture vapor contained therein. in this latter type of structure, the cooling water and the condensed vapor taken from the air are passed down to a drain.

In both these types of structures, a very substantial amount of the energy put into the machine is lost due to the fact that no use is made or attempted of the energy present in the water vapor carried with the air after it has passed over the clothes. For this reason, the most rapidly effective present-day clothes dryer requires the use of a 220 volt system; while 110 volt dryers are commercially available also, they use a substantially longer period of time for a drying operation than the 220 volt system, and this is primarily attributable to the relatively low efiiciency (both on 220 volts and 100 volts) which results from the carrying off of a very substantial amount of energy.

It is, therefore, an object of my invention to provide a clothes dryer constructed so that a substantial part of the energy in the water vapor coming from the clothes is retained and re-used in the system.

More specifically, it is an object of my invention to provide such a dryer wherein the desired result is obtained by the use of a substantially closed air cycle wherein the air containing the water vapor is cooled and expanded in order to cause the air temperature to drop and the vapor to condense; the vapor thereby gives up its energy to an air engine which assists a compressor device eiic-ctive to compress the expanded air after the water has been removed. The warm drying air resulting therefrom is then passed again through the. clothes.

in one aspect of my'invention I provide a clothes dryer having the conventional clothes receptacle with means for tumbling clothes within the receptacle. An air expander is provided having an inlet and an outlet, and an air compressor, similarly having an inlet and an outlet, is also provided, with both the expanding means and the compressing means being operated by common drive means. Suitable conduit means connect the receptacle to the expanding means inlet and to the compressing means outlet, the conduit between the receptacle and the expanding means inlet being associated with suitable cooling means for cooling air passing therethrough. My dryer also includes suitable liquid separator means connecting the expanding means outlet and the compressing eluding portion of this specification.

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further cooled down to its saturation point; thus, when it enters the expanding means, the expansion thereofby virtue of the further cooling which results-causes a condensing of the moisture vapor in die air. As the moisture condenses, it gives up energy, and because common drive means are provided for operating the expanding means and compressing means, this energy given up assists the common drive means in its operation thereby utilizing the energy in the water vapor to further the operation of the clothes dryer. It will be understood that expansion of the air actually assists the common drive means in two ways. First, the heat energy given up by the condensation of the moisture helps to expand the air and this tendency to expand the air provides a helping force on the expanding means. The use fulness of the heat energy in assisting the expanding means can readily be understood by analogy to the phenomenon of a cork in a bottle being forced out when the air in the bottle is heated. Second, there is a basic tendency of the air itself to try to expand once it is shut off from atmospheric air; this also results in a force assisting the expanding means.

The subject matter which I regard as my invention is particularly pointed out and distinctly claimed in the con- My invention, however, together with further objects and advantages thereof, will best be understood from the following description taken in conjunction with the accompanying drawing.

In the drawing, the single FIGURE is a schematic illustration of a clothes dryer which advantageously incorporates my invention.

Referring now to the drawing, I have shown therein a clothes dryer, generally indicated by the numeral 1, which in a conventional manner incorporates a housing or cabinet 2 with a backsplasher 3 having suitable controls 4 and indicating media 5. A generally cylindrical clothes tumbling basket or drum 6 is provided with perforations 7 in its cylindrical wall and is rotatably mounted by any suitable means; for instance, such means may include a shaft 8 secured to the back of the basket and rotatably fastened in a part of the housing 2 (the specific part not being shown). The basket is provided with suitable vanes 9 to assist in the tumbling of clothes placed therein, and is driven through a belt 1d from an electric motor 11 which may be of the conventionally used induction type. The belt passes over suitable pulleys 12 and 13 fastened respectively to the motor shaft and to the shaft 3 so that rotation of the motor causes rotation of the basket at a speed suitable to effect tumbling of the clothes.

Warm, .dry air is provided from a conduit, generally indicated by the numeral 14, so as to enter the basket on the left side thereof, and the air leaving the basket, after having caused migration of vapor from the clothes :lth a result lowering in the temperature of the air,

- passes out and away from the basket through a conduit 15 at the right side of the basket. As shown, suitable felt seals 16 and 17 may be provided at the top of conduits 14 and 15 respectively so that the air will be caused to pass through the basket in the desired manner rather than leaking around the outside of the basket. The motor 11 also drives a blower, generally indicated by the numeral 153, having an outlet 19 which discharges cool air over portion 20 of conduit 15 so as to cool the air therein for a purpose to be hereinafter more fully explained.

A compressor motor 21, which may also be of the conventional induction type, is provided with an output shaft 22 connected through a crank member 23 to a pair of pivotably mounted piston arms 24 and 25. Piston arm 24 is pivotablymounted to a piston head 26 which is reciprocable within a cylinder 27, movement of the piston 26 within the cylinder 27 changing the volume of the chamber 28 formed therein. Chamber 28 is formed with an inlet 29 and an outlet 30, the outlet connecting chamber 28 to conduit 14. Valve members 31 and 32 are respectively positioned to close the openings 29 and 39. Valve member 31 is arranged to move away from opening 29 upon an excess of pressure outside the chamber 28 with respect to the pressure therewithin, and valve member 32 is arranged to move away from opening 3:) upon an excess of pressure Within the chamber 28 with respect to the pressure in conduit 14. This may be effected, as schematically indicated, by securing the valve member 31 on the inner side of the chamber by a spring 33 and the valve member 32 on the outer side of the chamber by a spring 34. In this manner, when the pressure in chamber 28 is less than on the other side of valve member 31 there will, in effect, be a suction overcoming the action of spring 33 while at all other times spring 33, together with the pressure in chamber 28, forces valve member 31 into its closing position. Similarly, whenthe pressure within chamber 28 is relatively low, the spring 34 forces valve member 32 to its closing position, whereas when the pressure within chamber 28 rises approximately to or just above that within conduit 14 the very light pressure of spring 34 is overcome and valve member 32 is moved away from opening The piston arm 25 is pivotably connected to a piston head 35 which is reciprocably movable in a cylinder 36 so as to form a chamber 37 of varying dimensions. The chamber 37 has an inlet 38 connecting the chamber to conduit 15 and an outlet 39, the inlet and outlet being respectively closable by valve members 40 and 41. Valve member 40 is secured on an arm 42 which is pivotably mounted on a pin 43 and is pivotably connected to an arm 44 terminating in a cam follower 45. Operation of cam follower 45 is controlled by a cam 46 secured to rotate with a gear 47 driven by a timer gear 48 secured on the shaft 22 of motor 21. In this manner, for each full revolution of motor shaft 22 valve 40 will be opened for a predetermined length of time, and during the full revolution a complete cycle of movement of the piston head 35 from the position shown to a position adjacent the left end of the cylinder 36 and back again is provided.

Valve 41 is mounted in a manner similar to valve 40: through an arm 49 pivotably mounted at 50 and pivotably secured to a link 51 having a cam follower 52, the valve is operated by a cam 53 secured to rotate with a gear 54 driven by the timer gear 48. The particular periods of opening and closing of valves 40 and 41, as determined by cams 46. and 53 respectively, will be discussed herebelow.

Opening 39 communicates with a conduit section 55 separated from conduit 15 by any suitable means such as a barrier 56. Conduit 55 in turn communicates with an opening 57 leading into a water separator section 57a which may be of any conventional type, and is here shown as constituting a horizontal extending passage including a number of baffles 58. Y Preferably, the bottom of section 57a slopes gently downwardly toward an opening 59 which communicates with a drain (not shown) through a pipe 60. At the other, or left end, of section 57a an opening 61 provides communication with a conduit section 62 separated from conduit 14 by any suitable means such as barrier 63. The. conduit section 62 then communicates through opening 29 with the chamber 28 within cylinder 27.

During the operation of the machine, the motor 11 is energized and this causes rotation of the drum 6 at an appropriate tumbling speed in order to tumble clothes therein. It also causes cooling air to be passed from the outlet 19 of the blower 18 over portion 20 of conduit 15. At the same time, the rotor 21 is energized and this causes reciprocation of both piston heads 26 and 35, with each piston head going through one full reciprocating cycle for each revolution of the motor. The piston heads are preferably arranged, as shown in the schematic illustration of my invention, so that they both move in the same direction at any one time, that is, when piston head 26 is moving to the left to decrease the volume of chamber 2% piston head 35 is also moving to the left to increase the volume of chamber 37.

Following the passage of air through the machine, and starting within chamber v28, it will be understood that as the piston 26 moves to the left it compresses the air which has previously entered the chamber 2 8 through opening 29 and in so compressing it heats it. This air is relatively dry when heated, as will appear more clearly below. When the pressure within chamber 23 rises approximately to or just above that within conduit 14, the valve member 32 moves away from opening 30 and the air within chamber 28 is then forced out by the continued movement of piston 26, the air passing up through conduit 14. This air then passes into the rotating drum 6 through perforations 7 and, since it is dry and relatively warm, it causes vaporization of moisture from the clothes being tumbled Within the drum 6.

This evaporated moisture is then carried with the air as it continues to move, passing out of the drum 6 and into conduit 15. At this point, the air has lost a substantial amount of its heat, the heat having been given up to effect evaporation of moisture from the clothes. The air, as it passes through portion 29 of conduit 15 is then further cooled by the cooling blast of air from outlet 19 of blower 18, the Various components being so proportioned that the air is brought down quite close to its saturation temperature.

At the same time that piston head 26 had started its travel to the left, the same was also true of piston head 35. The cam 46 is so formed that as the piston head 35 starts its travel from its extreme right hand position toward the left, the valve 4-0 opens. Valve 40 is caused to stay open by cam 46 for a relatively small part of the total movement of piston head 35 to the left. As an example, the period during which it is open may constitute one quarter of the total piston stroke, after which cam 46 through engagement of timing gear 48 with gear 47 causes the valve 4%) to close. The continued movement of piston 35 to the left after valve 40 is closed increases the space within the volume of chamber 35 While at the same time there is no corresponding increase in the total amount of air within the chamber. As a result, the air is substantially expanded, and through the expansion the air is cooled.

Since the air entering had been caused to be substantially at saturation temperature prior to entering the chamher 37, the further cooling thereof causes condensation of the vapor which was carried with the air from the clothes within the drum 6, and this vapor in condensing gives up its latent heat of vaporization. This energy is thus used to assist in the movement of the piston 35 to the left, and therefore, as a result, the energy from the latent heat of vaporization assists the driving motor 21 in its functioning. In this manner, this energy is used rather than being merely exhausted from the machine as is presently true of commercially available machines. In addition, there is a tendency 'for the water droplets forming within chamber 37 to form about any particles of dust or lint which may have been entrained from the clothes within drum 6 as a result of the tumbling action.

Cam 53 is so shaped that, when the rotation of motor shaft 22'causes piston head 35 and piston head 36 to start to return to the right, valve 41 is caused to open. As a result, the movement of the piston forces the air out of chamber 37 through opening 39 into conduit section 55 whence it passes into the separator section 57a. In section 57a, the presence of the batlies causes. the air to change directions several times as it flows through the section so that the bafiies catch the condensed moisture with the air thus being dried and passing on through the section 57a and through opening 61 into section 62. The moisture caught on baffles 58 flows by the action of gravity down to the drain opening 59 so that it is then drained out of the machine through pipe 60. The cool expanded dry (but saturated) air then continues on its path through the conduit section 62.

Since at this time, the piston head 26 is moving from its extreme left hand position to the right, it efiects a suction action on valve 31 causing it to open so that the cool dried expanded air can pass into chamber 28. The air is thus drawn into chamber 28 as long as the piston head 26 moves to the right; when the direction of movement of the piston head is reversed, the valve 31 is closed by the increasing pressure within the chamber 28 and the valve 34 is caused to open when the pressure within chamber 28 approximates the pressure within conduit 14. At this point, by the compression action, the air has been heated to the point where it is capable of performing its clothes drying function as it passes again through the basket 6 from conduit 14.

It will be seen from the foregoing that the action is in effect one of cooling and expanding the air to condense the moisture therein, using the energy released by the condensation of the water in an air engine type device in order to assist the driving means in the operation of the dryer and then compressing the cool air after it has been dried to raise the temperature again for drying purposes. The action of the means driving the compressor is assisted by the energy released by the condensation of the liquid in the air engine expander so that a substantial amount of energy is conserved in this manner rather than being released immediately upon passing through the clothes basket.

It will be understood that, for purposes of clarity in illustration and explanation, a relatively schematic structure has been shown with a piston type air engine (the simplest to illustrate and explain) being used. However, in addition, other types of expander and compressor arrangements will come to mind as appropriate for use in my improved dryer. For instance, one other type of air expanding, drying and compressing means, which is particularly suited for use in a dryer of the type described herein, is described accordingly and claimed in copending application Serial Number 36,548 filed concurrently herewith by Kenneth K. Cooper, now Patent No. 2,984,- 088 and assigned to General Electric Company, assignee of the present invention. In addition, of course, it will readily be apparent that turbine type expanding and compressing means, both driven by a common drive arrangement as here, may readily be used; in that case the processes of expansion and compression are continuous and the valving arrangement required in the type of structure which has a definable cycle of operation (asin the case of a piston type device or as in the case of the structure claimed in the Cooper application) is not required.

Therefore, While in accordance with the patent statutes I have described what at present is considered to be the preferred embodiment of my invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and I therefore aim in the appended claims to cover all such equivalent variations as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a clothes dryer: a clothes receptacle; means for tumbling clothes in said receptacle; means for expanding air having an inlet and an outlet; means for compressing air having an inlet and an outlet; common drive means for operating said expanding means and said compressing means, said common drive means being formed so that air expansion and the resultant condensation of water in the air in said means for expanding air assists the common drive means; first conduit means connecting said receptacle to said expanding means inlet; second conduit means connecting said receptacle to said compressing means outlet; means for cooling air passing through said first conduit means to said expanding means inlet; and liquid separator means connecting said expanding means outlet and said compressing means inlet.

2. In a clothes dryer: a clothes receptacle; means for tumbling clothes in said receptacle; means for expanding air having an inlet and an outlet; means for compressing air having an inlet and an outlet, said expanding means and said compressing means being of the type having a definable cycle of operation during which a predetermined quantity of air is expanded and a predetermined quantity of air is compressed and said means are then returned to their initial positions; first, second, third and fourth valve means controlling said expanding means inlet and outlet and said compressing means inlet and outlet respectively; control means causing said first valve means to open for a predetermined period during the initial part of the expansion of said expanding means; control means causing said second valve means to open during a substantial part of the return of said expanding means; said third valve means being responsive to return of said compressor means to open; said fourth valve means being responsive to a predetermined amount of compression of said compressing means to open; common drive means for operating said expanding means and compressing means, said common drive means being formed so that air expansion and the resultant water condensation in said means for expanding air assists said common drive means; first conduit means connecting said receptacle to said expanding means inlet; second conduit means connecting said receptacle to said compressing means outlet; means for cooling air passing through said first conduit means to said expanding means inlet; and liquid separator means connecting said expanding means outlet and said compressing means inlet.

3. The apparatus defined in claim 2 wherein said first and second valve control means are operated by said common drive means so as to be synchronized with the operation of said expanding means and said compressing means.

4. The apparatus defined in claim 2 wherein said expending means comprises a piston and cylinder arrangement, said compressing means comprises a piston and cylinder arrangement, and said drive means com rises an electric driving motor and means connecting said motor to both said pistons.

5 The apparatus defined in claim 4 wherein said pistons are arranged so that said expanding means is on an expansion stroke when said compressing means is on a compression stroke.

'6. The apparatus defined in claim 1 wherein said clothes receptacle comprises a perforated drum member mounted for rotation on a horizontal axis, and said means for tumbling clothes in said receptacle comprises electric motor means connected to said drum to rotate said drum at clothes-tumbling speed.

7. The apparatus defined in claim 1 wherein said cooling means comprises blower means arranged to blow cool ing air over said first conduit means.

8. In a clothes dryer: a clothes receptacle; means for tumbling clothes in said receptacle; means for expanding air having an inlet and an outlet; means for compressing air having an inlet and an outlet; common drive means for operating said expanding means and said compressing means, said common drive means being formed so that air expansion and the consequent water condensation in said means for expanding air assists said common drive means; first conduit means connecting said receptacle to said expanding means inlet; second conduit means connecting said receptacle to said compressing means outlet; liquid separator means connecting said expanding means outlet and said compressing means inlet; and means ar- I? ranged to 2001 air after it has passed through said re- 822, 39 ceptacle and prior to its entering said compressing means 1,402,716 inlet. 1,799,248 1,866,346 References Cited in the file of this patent 5 2 676 413 UNITED STATES PATENTS 2,742,708

271,859 Jones Feb. 6, 1883 8 Bedortha June 5, 1906 Candor Ian. 3, 1922 Reinhardt Apr. 7, 1931 Clark July 5, 1932 Shewmon Apr. 27, 1954 McCormick Apr. 24, 1956 

